MY truck starts fine but within the first 5 minutes if driving it starts to run rough, loses power and will backfire thru the exhaust when I try to accelerate. It will do this for 2-3 minutes and then smooth out and run perfect. It is worse in the winter but also does it in the summer and is getting more frequent. Also if I start it and just let it sit it will do the same thing such as rough idle etc. and then clear up within a couple of minutes.

I have done a total tune up complete with new plug wires, replaced the MAPP sensor, PCV valve, had the timing checked and replaced the water temp sensor. These changes have helped but it is still doing it. It acts like the gas mixture is too lean. Any suggestions would be greatly appreciated.

Cars & Trucks - Ford - Ranger - 1992 Ford Ranger